Broan, 355RSO, Powered Attic Ventilator, Black, Solar PAV, Fans, Roof Mount Roof Mounted Low Profile Solar Powered Attic Ventilation Fan, Up to 1600 Sq Ft, 5 Year Warranty, 20W SolarAll attic fans, powered or solar vent out the hot air built up within the attic, but a solar unit offers additional benefits not possible with a powered product. Because a Broan Solar PAV turns on at dawn, it goes to work immediately, first to eliminate the moisture that has built up from the cool overnight air, and second, to prevent heat build up before it has a chance to build up to the point of convection. A standard PAV has to reach a high temperature before the thermostat kicks in and tells it to start working. By this time the moisture has already worked its way into the insulation and the walls, doing its damage. Because it has to play catch-up the PAV is already starting out at a disadvantage and must run all day. Driven off AC power, a PAV can be noisy emitting harmonic noise, and although it is possible to override the thermostat and let it run, the motor is not designed to handle this constant demand.7/8 High Profile - Remote Panel20 Watt, State-Of-The-Art Solar Panel Circuitry Captures Sunlight Even On Overcast Days. Totally Weatherproof Panels Designed For Optimum Efficiency Constructed Of Tempered Glass To Resist Hail And Extreme Weather ConditionsDome And Base Molded With Uv-Stabilized Abc Color-Dyed Plastic To Prevent Damage From Sunlight And Provide Greater Stability. Low Profile, Square Design Integrates Well With ShinglesHurricane Rated To 140 Mph WindsQuality Hardware Used Throughout. 16Awg Stainless Steel Brackets And Bolt, Nuts And Self-Tapping Screws For Stability And Long lifeWhisper-Quiet, Direct Current, Variable Voltage, Sealed Ball Bearing And Hardened Shaft Motor With Steel Motor Housing Dynamically Balanced For Superior PerformanceSpecially Designed One Piece, 12 Aluminum 5 Blade Fan Pitched For Maximum Air Flow. Heavy Gauge, Stainless Stee